"Cagdas Ozgenc"
Greetings.
Why does Haskell let you write functions that are not a part of type class? For example instead of
the goal of type class is to allow overloading of function, so for example id x = x is not subject to overloading => no use to put it in a type class.
elem :: Eq a => a -> [a] -> Bool map :: (a -> b) -> [a] -> [b]
class Container a where elem :: Eq b => b -> a b -> Bool map :: (b -> c) -> a b -> a c
would define methods that can work on all containers, and create a discipline to write more reusable and generic functions.
yes, that's right that map and elem could be put in a type class, but that's hard and require more advanced feature of haskell (here you use constructor class but you need more : multi-parameter class, ....) see http://www.cse.ogi.edu/~mpj/fds.html.
Thanks
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